1. The Technical Field
The present invention relates to food products and to their methods of preparation. More specifically, the present invention is directed towards aerated frozen dairy desserts and liquid mixes therefor comparable to high fat ice creams but which although milk based are low in fat. In its method aspect, the present invention resides in methods by which frozen dairy desserts and liquid pre-mixes can be prepared.
2. The Prior Art
Dessert products intended to be consumed while frozen have been known for a long time. The principal frozen dessert products are ice cream, ice milk, mellorines, sherbets and water ices. Ice cream is a frozen food product prepared from a mixture of dairy ingredients, sweeteners, stabilizers and emulsifiers which is pasteurized, homogenized, flavored and frozen usually under agitation while air is incorporated. Ice milk is similar to ice cream but contains less milk fat. Mellorine is similar to ice cream except that the butterfat is replaced with vegetable fats. Sherbet is a frozen dessert characterized by its tart flavor which results from adding fruit or fruit juices along with dairy ingredients and may also have added fruit acid. It is prepared from the same basic ingredients as ice cream, although the maximum total milk solids content is about 25 percent that of ice cream. Frozen water ices are a frozen product prepared from water, sugar and fruit juices, stabilizer, with or without additional acid and color, and containing no dairy product. Water ices differ from ice cream in that the overrun, or amount of air incorporated during the manufacturing process is substantially lower than that of ice cream. Governmental standards, both federal and state, of identity exist for each of these frozen desserts. Ice cream by these standards must comprise at least 10% and can comprise up to 18% fat. Ice cream manufacture is considered a highly developed art. The formulation, preparation and general description of ice cream is exhaustively described in "Ice Cream," fourth ed. by W. S. Arbuckle, The Avi Publishing Company, Inc., Westport, CT 1986.
In general, the higher the fat level in a frozen dessert, especially ice creams, the more pleasing and appetizing has been its texture and flavor. Such preferred ice creams have been sometimes referred to as "premium" ice creams. In response to current consumer taste fashions, premium and even "super premium" ice creams have become increasingly popular. In addition to very high fat contents of typically about 14% to 18%, such ice creams are also frequently characterized by high milk solids and low degrees of overrun, i.e., the amount of air incorporated into the composition, resulting in higher densities. While popular and organoleptically desirable, these premium ice creams with higher fat contents are more costly due to the relatively high cost of the butterfat ingredient. And, too, the calorie content of the frozen dessert is higher. Also, cholesterol levels are higher.
For these reasons, the prior art includes many attempts at providing a low fat frozen dessert which nonetheless exhibits the desirable organoleptic attributes of the high fat or even super premium ice creams. In spite of these many attempts and contrary to the many self proclaimed teachings that equivalent attributes have been obtained in a low fat composition, prior to the present invention there has not yet been a good low fat, high quality, milk based aerated frozen dessert.
Ice cream generally comprises butterfat, milk solids non-fat ("MSNF"), sweeteners, water and minor amounts of everything else, e.g., flavors, salt, stabilizers, emulsifiers, etc., although large amounts of other materials, e.g., nuts, fruit, cookie chips, etc., can be distributed throughout. By a "reduced fat" or equivalently a low fat frozen dairy dessert is meant a product having the fat-like organoleptic attributes of an ice cream prior to flavor addition having 10% to 18% butterfat, but having a fat level of less than 10%, i.e., less than ice cream. By "no-fat" or "non-fat" is meant a frozen dairy dessert which has no added butter or vegetable fat. Such products typically will have fat levels of less than 0.5%.
If in the provision of a low fat or reduced fat frozen dairy dessert, all or part of the butterfat is to be replaced, then equivalent amounts of solids must be supplied by the MSNF and/or the sweeteners or other ingredients. However, in view of the vast array of milk based ingredients and their potential modification through processing, the large variety of sweeteners, emulsifiers and stabilizers, their potential combinations are nearly infinite. Unfortunately, a result is that the teachings of the prior art are frequently self contradictory. One reference may teach the criticality of certain stabilizers, while another may teach that such materials are optional or even to be avoided. Some references may teach the equivalency of some materials while other references may directly so contradict.
U.S. Pat. No. 3,345,185 (issued Oct. 3, 1967 to Pisani et al.) for example, discloses a low fat, milk based aerated frozen dessert wherein the butterfat constituent is replaced with non-fat milk solids from powder or condensed skim milk. To overcome the "sandiness" defect caused by high lactose levels resulting from this substitution, higher levels of corn syrup solids are employed. (See also U.S. Pat. No. 3,407,075 issued Oct. 22, 1968 to Barker) which shows a reduced fat butter-like product wherein milk solids partially replace butterfat. In U.S. Pat. No. 3,510,316 (issued May 5, 1970 to Decker) a similar product has added fine crystalline lactose to prevent sandiness caused by lactose crystallization.
A reduced fat, milk based, aerated frozen dessert is disclosed in U.S. Pat. No. 3,128,193 (issued Apr. 7, 1964 to Hilker) which is made using a special high sheer mixing step. The high sheer step imparts greater fat-like properties to the product using the reduced fat amounts. U.K. patent 1,446,144 (published Aug. 18, 1976 to Kraftco) discloses a reduced fat, aerated frozen dessert using special emulsifiers to impart fat-like properties. A similar approach but employing different emulsifiers and optionally certain stabilizers is disclosed in U.S. Pat. No. 3,800,036 (issued Mar. 26, 1974 to Gabby et al.) or in U.S. Pat. No. 3,809,764 (issued May 7, 1974 to Gabby et al.). In U.S. Pat. No. 4,435,439, an aerated frozen low fat dessert is disclosed of the sherbet type using both emulsifiers and stabilizers to improve the sherbet's attributes. Since emulsifiers affect fats, some fat must be present in order to obtain the benefits of the emulsifier. Thus, while emulsifier manipulation may have benefits in providing reduced fat frozen dairy desserts, such approaches have little utility in connection with no fat dairy desserts.
U.S. Pat. No. 4,400,405 (issued Aug. 23, 1983 to Morley et al.) discloses a dietetic lower fat aerated frozen dessert employing high levels of stabilizers, emulsifiers and polyhydric alcohols. A reduced fat aerated frozen dessert with polyhydric alcohols is disclosed in U.S. Pat. No. 3,928,649 (issued Dec. 23, 1975 to Cobb).
A reduced fat milk based aerated dessert prepared at home by static freezing from a two component mix is described in U.S. Pat. No. 4,282,262 (issued Aug. 4, 1981 to Blake). While one component is a concentrated milk blend which is specially heat treated to improve the functionality of the milk constituents by nearly complete protein denaturization, heavy reliance for end product attributes is placed upon use of certain casein reactive gums as stabilizers.
More recently, as whey protein concentrates have become more widely available, their use in ice cream products has become more common. For example, U.S. Pat. No. 4,497,841 (issued Feb. 5, 1985 to Wudel et al.) discloses a reduced fat, milk based aerated frozen dessert wherein whey protein concentrate is preferably employed in partial substitution for and along with MSNF (milk solids non-fat). Fructose is used as the sweetening agent. Conventional emulsifiers and stabilizers are used to improve the dessert properties.
In U.S. Pat. No. 4,333,953 (issued June 8, 1982 to Trzecieski) a creamy, low fat aerated frozen dessert is described using high levels of milk solids not-fat for the fat and containing lactase which by hydrolyzing lactose into glucose and galactose is taught to reduce the problem of sandiness. The U.S. Pat. No. 4,333,953 patent also teaches that demineralized whey protein can be used in partial substitution for the MSNF. However, flavor problems exist when many types of whey powders are added.
In spite of these numerous prior art attempts, to date, no low fat aerated, milk based frozen dessert has enjoyed commercial popularity.
The difficulties in formulating a low fat milk based aerated frozen dessert are compounded by lactose crystallization as well as the freezing point depression that occurs when fat solids are replaced by lower molecular weight compounds. Stability problems are more severe with bulk frozen items compared with soft serve. Soft serve frozen products are typically consumed shortly after preparation. In contrast, bulk frozen ice cream typically is stored through various distribution channels before sale. Due to the inevitable temperature fluctuations that occur during this distribution, the heat shock stability of ice creams is very important. Unfortunately, low fat ice creams are particularly vulnerable to heat shock instability by virtue of the absence of the fat component.
Surprisingly, the above problems have been overcome and superior aerated frozen dairy dessert compositions have been developed which exhibit the organoleptic attributes of high fat ice creams which nonetheless is a low fat composition. The dairy dessert compositions are prepared with high levels of whey protein and with specific casein to whey ratios.